


Periculosus

by byzantiumthistle



Category: Gravity Falls
Genre: Angst, Drama, Gen, Humor, Hurt/Comfort, Mystery, Supernatural - Freeform
Language: English
Status: In-Progress
Published: 2015-06-24
Updated: 2015-06-27
Packaged: 2018-04-05 21:18:34
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 4,074
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4195245
Author URL: https://archiveofourown.org/users/byzantiumthistle/pseuds/byzantiumthistle
Summary: <blockquote class="userstuff">
              <p>Merging two dimensions was not an easy task, but it was one Bill Cipher had devoted a long time to; ten years, now. But before he had a chance to use the energy he'd stockpiled, the strange mental tugging he'd felt towards Gravity Falls ever since he'd left forced him to rethink his plans.</p><p>Meanwhile, Dipper Pines has been experiencing strange nightmares and memories ever since that tricky dream demon possessed his body ten years ago. The Journal had nothing to say about this unknown phenomenon. Could Bill Cipher himself offer insight into what's happening to him?</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> This fanfic might be a little different (in terms of writing) than most. Firstly, it's being written by two people; Paige and Quinn. Secondly, there will be two third-person perspectives being written and alternated between; Paige will be writing Bill's parts and Quinn will be writing Dipper's parts; we'll both be writing Mabel's and the other character's parts. Other than that, this fic focuses mainly around mental illness caused partially by trauma and partially by supernatural implications. The issues we'll be speaking most about are flashbacks (and other PTSD-related symptoms), dissociation (referred to as "blackouts"), insomnia, depression, manic episodes, psychosis, and night terrors. If you're ever triggered by any of these things, please keep that in mind before/while you read. 
> 
> You can find us on Tumblr!  
> Paige: agent--montana.tumblr.com  
> Quinn: mynetworknameisunicornbutts.tumblr.com
> 
> We'll do our best to keep our story updated regularly. And don't hesitate to send us questions/concerns/suggestions to our ask boxes on Tumblr. 
> 
> Thanks for reading! - Paige & Quinn

**_"You want me gone? I can do that! But know this, kiddos; this isn't over. Actually, it's just beginning! The prelude to the prelude! You kids should prepare for what's coming; I'll give you a head start! Next time you see me, the human race will experience a world like no other, and you two will be my guests of honor! Just be patient!"_ **

* * *

 

     The demon had not been exaggerating the warning he'd given the Pines twins; if anything, it had been an understatement. This was what he had waited and wished for for centuries; the plan to put all others to shame. He'd marginally oversold his resume when he called himself omnipotent; in the Mindscape, there was nothing he couldn't do. Infinite power was, indeed, something he possessed; but when it came to the waking world, there were some _roadblocks_ in his way. The most troublesome of these was undeniably the fact that without a human vessel, he couldn't even _affect_ it; and even if he were to acquire one, say, via possession, his powers were limited by the aforementioned _insufferable_ meatsack.

     Now, factor in the Nightmare Realm, the dimension Bill called home. With enough power, and it _was_ a lot, one could, in theory, merge the conscious world with the unconscious; two dimensions for the price of one! For someone as power-hungry as he unmistakably was, having unlimited control just the _tiniest_ bit out of your reach was like starving with a sandwich right in front of your face. And with the effects the Pines' portal had on the stability of their dimension, there was no better opportunity to just reach over and take a bite.

     Bill was a patient being so long as he was on the right track; if he knew he was indomitable, he would wait as long as it would take with no complaints or restlessness. The ten years spent gathering energy went by in the blink of an eye; were his existence compared to a decade, it could effectively be considered a mere ten minutes. Ten minutes that were very, very well spent, in his opinion; ten minutes that, to him, were irreplaceable.

     Bill _was_ a patient being, that fact remained; but not even the most tolerant person would be pleased to have everything they'd worked for taken away from them in the span of five minutes -- _not_ comparatively speaking. Multiply their frustration by ten thousand, and you've arrived at one tenth of the fury the demon currently felt; patience was conclusively thrown out the window and into the bottomless pit.

     He had been _so close_ ; so close to success, to satisfaction. Metaphorically, the sandwich was in his hands and inches from his mouth. In retrospect, the demon realized that he should've given the strange phenomenon he'd been experiencing his full attention before it did something like _this_ ; but the thirst for power had been too strong, too overpowering and all-consuming, and he had subsequently ignored what was now resulting in his downfall.

     It had been ten years since Bill had left Gravity Falls (mostly) alone; for a demon of his age and rank, it felt like nothing. It passed by in the blink of his solitary eye. It left him unaware of how _long_ that was for a tiny consequence to snowball into a disaster for everything he'd worked for -- until now.

     A short while after he left, the demon began feeling an odd, mental tugging towards Gravity Falls. At first, it could've been compared to a human's nagging sense of worry upon leaving home; did they leave the oven on, or the garage door open? It was easily dismissed, and that was what he did. The consequence of having unlimited knowledge and vision was that there was often so much going on that Bill was frequently too busy with more pressing matters and drawn away from things like worry. So while the tugging grew stronger, so did the urge to dismiss it; it became an annoyance, an interruption, something that deserved none of his attention.

     Now, however, it could no longer be ignored. What had once been a slight tug was now a yank so hard that it traversed dimensions, forcefully pulling him from his own and into the waking world; where if he wanted to survive, the demon would need to take a human form. And for him to do that and retain his powers, he couldn't just steal any vessel, even if he had the time; he would need to create one. And that took quite a bit of energy; roughly _all_ of his reserve that he needed for his plan.

     It had all happened in too much of a blur for any of that to be a conscious decision. The pull was so sudden and so strong that Bill's actions were not a result of any deliberation, but rather that of an automatic survival instinct. Had he the time to think for even a _second_ , he was sure he could've found an alternative, but now he was stuck in an intolerable fleshbag with just enough energy to lift a _finger_.

     Yellow eyes opened in a panic to the damp darkness of a large cave, darting around quickly in an attempt to get his bearings. He was in Gravity Falls, he knew that; even if he didn't recognize it, a monkey could've figured that out given all of the preamble Bill was finally paying attention to. The smell of tree sap overpowered his nostrils, and the sudden onset of such overwhelming senses made him shut his eyes and desperately try to just turn them _off_.

     'Time is meaningless' was a sentiment he held close to his heart, but it tended to hold more value to demons stuck propped up on a rock made, ironically, of iron, unable to move for -- what was it now? -- 36 hours? Demons and iron didn't mix, a lesson he'd learned centuries ago; after this amount of time, he didn't need to feel his back to now it was burnt. The pain that it gave off only fueled the fury that, now that he'd had time to deliberate, the demon had decided to direct at his favorite pair of twins. After all, who else could possibly be to blame for this situation? They had the motive, the resources -- all evidence pointed at them, and Bill was far from pleased.

     Naturally, this meant that the Mystery Shack was number one on his list of travel destinations, and he just couldn't _wait_ to make his entrance. If he had had the energy, Bill would've been knocking on their door the moment he had arrived, but even with most of his powers intact in his current form, expending that much energy in so little time took too much of a toll on him to allow him his impatience. Finally, however, the time had finally come that the demon was able to remove himself from his rocky cage and visit the topics of interest.

     The bright light of morning contrasted drastically with the darkness of the cave, and the exhausted demon took several seconds to adjust. His left eye refused to entirely, and with growing frustration, Bill forced it shut and continued on his way. He could tell it was morning, but the exact time was beyond his current knowledge; he wondered if any of the Pines family was even _awake_ yet. Actually, he decided, that would definitely be to his benefit.

     And so, when footsteps finally neared the living room, their owner was faced with a Bill-sized mess of blankets on the couch, and a voice laced with cruelty sarcastically calling, "Hey, Pine Tree, you got any food in here?"


	2. Chapter 2

**Notes for the Chapter:**

> Please see the first chapter for complete notes and warnings. 
> 
> You can find us on Tumblr!  
> Paige: agent--montana.tumblr.com  
> Quinn: mynetworknameisunicornbutts.tumblr.com
> 
> We'll do our best to keep our story updated regularly. And don't hesitate to send us questions/concerns/suggestions to our ask boxes on Tumblr. 
> 
> Thanks for reading! - Paige & Quinn

_**"Seems to me one little puppet is a small price to pay to learn all the secrets of the universe. Besides, what's your sister done for you lately? How many times have you sacrificed for her, huh? And when has she ever returned the favor? ... Tick tock, kid."** _

* * *

 

     Dipper's body shot upright in a start, his lungs gasping for air. When was the last time he'd had a restful, fulfilling sleep? Ten years ago today. At least he remembers _that_ clearly. How could he forget? Today was the tenth anniversary of Dipper's worst mistake; making a deal with Bill Cipher. It was the day he lost control of his own body; the day his sister -- the only friend he's ever had -- was almost killed. It's safe to say that Dipper considers that day one of the worst in his twenty-two years of life.

     Other than the vivid flashbacks he experiences in his nightmares every year on this day, everything else regarding his dreams are nothing more than a blur. Aside from one reoccurring nightmare that never seems to leave him alone. He's walking through a maze of doors resembling Stan's Mindscape; everything is black and white; there are triangles everywhere; carvings of singular eyes, too. A door with the numbers "1865" crudely etched into the wood swings open; there stands a man in a top hat and suit, complete with bow tie and cane. He distinctly remembers wondering if he'd ever seen Bill with a cane before. Then the man is running, seemingly from what appears to be an angry mob, complete with blazing torches and all. He finds somewhere safe to hide and catch his breath, though that affair is abruptly cut short by the appearance of a unknown entity; a supernatural being Dipper had never seen. This apparition seemed to be a demon of some sort, outstretching his hand toward the man. That's where Dipper's breath caught in his throat each time this nightmare came to him. He silently urged the man not to do it, nearly screaming when their hands met and shook. Not a second later, a hole opened in the floor right beneath his feet and the man fell through, yelling and laughing as he did. On cue, just like every other time, the door slammed shut and Dipper was left to stand there, shaking. Then his eyes would snap open, like he were forced into consciousness. It was almost as if he had access to someone else's Mindscape and they didn't want him snooping around.

     Shaking his head free of the thought, Dipper stood to quietly tiptoe his way to the bathroom, so as not to wake his twin sibling. However, when he tried to stand, an unwelcome pain rang throughout his head, causing him to fall back to his previous position, vision blurring to blackness. Once his vision cleared, he understood why his mattress suddenly felt rock solid.

     "But.. I was in the Shack. How did I get out here..?"  
  
     Lines of trees surrounded the brunet; grass, moss, and dirt covered his hands. A very ominous feeling crept up his spine as he stood a second time, successfully maintaining his balance with the aid of a tree's trunk. He took that moment to glance at his watch -- exactly 10 AM -- and analyze which part of the forest he'd ended up in, concluding that he was very close to the abandoned church where they saved Waddles all those summers ago. But, why there? He had no interest in that place anymore; all of the dinosaurs they discovered were taken by the government and never seen again. There was nothing left to find down there. Right?

     As if he had teleported somehow, he found himself directly in front of the church with no memory of moving from his new tree friend. The pain in his skull was growing in intensity and his body's new found habit to twitch every now and then was acting up far more than he deemed safe. Dipper could feel his breaths getting short and his knees threatening to give way beneath him. All things considered, he spun on his heel and sprinted as quickly as he could possibly manage from the abandoned church, exiting the forest within mere minutes.

     And there was the Mystery Shack, in all its run down glory. Dipper had never been so relieved to see the tiny cabin; it felt as if it had been hours since he'd last been inside. But, logically, it had only been a few minutes, at most. That's what Dipper kept telling himself, anyhow.

     "Hey, Pine Tree, you got any food in here?"

     Now inside their cramped living room, Dipper froze in his tracks, the relief he so previously felt quickly morphing into fear. There, bundled in, presumably, 4-6 blankets, lay Bill Cipher; humanoid, but not quite enough. His ears were pointed; his only visible eye was very clearly not of human origin. Why would he bother taking a human form if it weren't convincing enough?

     Initially, all Dipper could do was stare. He could hardly tell if he was staring out of fright, surprise, fury, or all of the above. But, one thing was certain; he had to protect Mabel at all costs. So, fueled by his motivation to keep his sister safe, Dipper rustled through his jean pocket, revealed a small apothecary bottle containing multiple kinds of salt and held it before him, daringly pushing the pad of his thumb against the cork stopper.

     "Get out."


	3. Chapter 3

**Notes for the Chapter:**

> Please see the first chapter for complete notes and warnings.
> 
> You can find us on Tumblr!  
> Paige: agent--montana.tumblr.com  
> Quinn: mynetworknameisunicornbutts.tumblr.com
> 
> We'll do our best to keep our story updated regularly. And don't hesitate to send us questions/concerns/suggestions to our ask boxes on Tumblr.
> 
> Thanks for reading! - Paige & Quinn

      _"Get out."_

     Those two words alone were all it took for him to momentarily lose control of his fury, his eyes flashing bright red for several seconds as he fought to regain his composure. The demon flinched visibly when the salt was revealed, something he was very rarely known to do unless his mental state was seriously questionable. Bill knew he was vulnerable _and_  desperate, a combination he never found enjoyable; it meant he would have to back down, or at least _manage_ his anger for the time being and communicate with some degree of civility. And the demon had gone from being exceedingly close to limitless power to being threatened at will by a _human_  in a matter of days, so his ability to be civil was _painfully_  low.

     "Kid, do you have _any_  idea what you've cost me this time? Everything!" he began, his voice slowly beginning to rise as his eyes erratically flashed between yellow and crimson. " _You_  brought me here, _you_  forced me out of my own dimension, and now you have the audacity to tell me to _leave_?"

     "What are you talking about?" Dipper questioned, in an easily curious and angry tone, "I haven't done anything to you!"

     " _Really_ , Pine Tree?" he demanded, eyes narrowing in disapproval before he continued. While a part of him recognized that Dipper was not the type of person to, in this situation, play dumb, but he disregarded that fact for the sake of following the blind rage he felt. After all, he really couldn't think of any alternative explanation. "Do you think I just decided to waste _all_  of the energy I'd saved up to create a human form just to survive being yanked through dimensions? No! And the only one who has the motive _and_  the means is _you_ , kid. So explain yourself."

     "I'm just a worthless 'meatsack', or whatever you call us, remember? There's no way I could've possibly dragged you here, if I wanted to. Which I didn't, I might add." Despite his confusion regarding the situation, Dipper kept the bottle held firmly in his grasp; he was not a risk taker anymore, especially when Bill was around to mess things up. "When did you even get here?" he asked, bringing his free hand up to his head when a jolt of pain shot throughout his skull.

     "A meatsack that's managed to ruin everything for me _before_ , isn't that right, kid?" the demon reminded, eyes flickering cautiously down to the bottle of salt every few seconds. Another frustrated retort was cut off mid-thought when Bill's attention shifted to the unexpected pained reaction in the human in front of him. "What, is your big head finally--" His derision was quickly shortened by a pang of what he could only assume was pain similar to what Dipper was experiencing, and the demon forced his eyes shut tightly for several seconds, waiting for it to pass. When it once again became manageable, he slowly reopened them and stared at the brunet, and the disdain that filled them clearly yet silently demanded 'What did you _do_.'

     The brunet couldn't help noticing Bill's pained reaction that just happened to coincide with his own. But, he didn't have time to question it. Dipper needed the demon to believe him. "Okay, I'll admit that I _did_ ruin your devious plans before, but, I swear, I didn't do anything this time! ..I just wanted to enjoy my last summer here." He spoke the last sentence quietly, his tone laced with bleakness.

     For several long seconds, the demon did nothing but stare at the brunet with serious contemplation. The rage that was fueling his stubbornness needed more energy than he had to keep burning, leaving him with the cold reality that they both might be telling the truth; which would mean that there was something bigger than he'd expected going on here. Bill did not welcome the idea, but arguing in circles just to avoid accepting what he'd rather not believe was pointless and time-consuming.

     "...Fine, I'll give you the benefit of the doubt, just this once," the demon finally decided, mouth now forming a thin line. Reasonably speaking, Dipper had no reason to lie about this; if he _had_  somehow brought him here, he would know that he had the upper hand. Bill was sure he wouldn't feign ignorance if he finally had power over the demon that had nearly ruined his life; if he wasn't even the slightest bit smug, Bill would be sincerely appalled. The last, quieter sentence threw him off, however, and a wave of curiosity urged him to question it. Inwardly postponing that interrogation, he continued with the matter at hand. "Then we've got a problem, Pine Tree."

     "No kidding," he responded, finally dropping the bottle of salt and sinking onto Stan's armchair with a sigh. Dipper tucked the bottle back inside his jean pocket, being sure to show Bill that he still had it on his person. "God, Stan is going to kill me."

     "He's the _least_  of our problems, kid," the demon replied, followed by a quiet sigh of relief as the salt was no longer an immediate danger. Then again, he was stranded in the home of some of the most _troublesome_  humans he'd ever encountered, topped off by some possibly disastrous and entirely unexplained circumstances; the comforted feeling was as fleeting as they came. "And you have _no_  idea what's going on?"

     "No, for once, I don't. I'm sure that amuses you," he muttered, already losing patience with the situation, "I just need to keep this from Mabel--"

     "Diiiid someone say 'Mabel'?!" the female twin enthusiastically questioned, appearing from seemingly out of nowhere. Then, to Dipper's inconvenience, she noticed the blanket-covered demon resting on their love seat. "Oooh! Who's this? Finally got yourself a boyfriend, huh?"


	4. Chapter 4

**Notes for the Chapter:**

> Please see the first chapter for complete notes and warnings.
> 
> You can find us on Tumblr!  
> Paige: agent--montana.tumblr.com  
> Quinn: mynetworknameisunicornbutts.tumblr.com
> 
> We'll do our best to keep our story updated regularly. And don't hesitate to send us questions/concerns/suggestions to our ask boxes on Tumblr.
> 
> Thanks for reading! - Paige & Quinn

      "Oooh! Who's this? Finally got yourself a boyfriend, huh?" Mabel asked, playfully nudging her brother with her elbow, that signature Mabel laugh of hers ringing throughout the room.

      "No! Mabel!" Dipper lightly pushed her away, gesturing toward the demon, "That's Bill!"

      "The triangle guy?! ..But, he's not a triangle anymore," she observed, looking seriously puzzled.

      "Yep, the triangle guy, in the flesh! Literally, unfortunately. Can't call me an isosceles monster anymore, Shooting Star. It's a shame; I really liked that one," the demon commented idly, slowly pulling himself up into a sitting position with a sigh.

      Mabel pursed her lips and puffed her cheeks, attempting to look annoyed, but not entirely succeeding, "I'll call you whatever I want! You... butt face."

      The male twin shook his head at her effort, quick to move on to the next topic at hand, "Let's _not_  do this right now, okay, guys? We need to figure out how to hide _you_  from Stan. Or what to tell him when he finds out you're here, which will inevitably happen."

      "Tell him I got hurt in the Mystery Shack and I'm suing him for everything he's got. That'll give him a scare!" Bill suggested with a wide grin, the thought of terrorizing their Grunkle giving him marginally more energy.

      " _No,_ " Dipper replied, clearly expecting Bill's remark, "We need a believable, and less heart attack inducing, lie. But, _someone_  doesn't look human enough for that to work. Not to mention the oddly skinny top hat _literally floating_  above your head."

      "Oh, you're right, I'm _sorry_ , Pine Tree. It's almost like I'm _not_  human, and _not meant to be here_. But here, let's solve that problem!" the demon exclaimed, snapping his fingers as a blue light surrounded the hat, moving it onto the male twin's head. "Good luck getting that off."

      "That's--" The brunet's cold retort was cut short when the hat unexpectedly flew towards him. Dipper had no time to move before the head wear found its new residence. " _Hey!_  Get your stupid hat off of me!" he shouted, frustratedly tugging at the hat's fabric in an attempt to remove it. Unfortunately, it seemed to be glued to the air just above his head.

      "Stupid? You just earned yourself another _ten_ hat-minutes, kid!" Bill declared, crossing his arms as an act of defiance as if to reinforce that no fingers would be snapping again any time soon. "Hey, maybe it'll teach you how to dress! It's a classy hat, Pine Tree. Flannel isn't classy."

      " _Hat-minutes?!_ " Dipper exclaimed, voice cracking a bit when it rose, "At least _I_  don't try too hard to look fancy all the time, you--"

      "Boys, boys," Mabel chimed in, "There's no need to get touchy over your own styles. Bill is dapper and Dipper is casual. What's wrong with that?" she asked, attempting to cease their arguing.

      A wide grin spread across the demon's features as he listened to the twins, snapping his hat back over to him. "Listen to us, arguing like _friends_. I mean, did Shooting Star just defend me? Glad everything's water under the bridge, now that I'll be living here!" Bill was fully aware that nothing had been resolved and he was treading on very thin ice, but his smug sarcasm, if nothing else, addressed the tension looming over the three of them.

      Mabel's optimism seemed to drain from her face as she turned to look at her brother. She realized she needed to take the situation more seriously, but it was very difficult for her to cope when she wasn't being optimistic or silly, especially when Bill was around. The brunette knew that Dipper's summer was already ruined in his mind and she didn't think she could live with that. If anything, she was going to do her best to make their last summer in Gravity Falls a good one, even if they had to house a demon.

      "..Mabel," Dipper spoke quietly, returning her saddened glance, "Let's talk somewhere private," he concluded, lightly grabbing her arm and dragging her off to the kitchen, where he could still keep an eye on Bill without being interrupted.

      The female twin gave Dipper a slightly worried look, though she was still trying to smile. "Is he, like... stuck here? He said he's not meant to be here, right? Does that mean he's not planning anything this time?" She stopped herself before she asked any more questions, letting her brother explain.

      "I guess? I mean, initially, he thought that _I_  brought him here, which means he's here against his will somehow. But, the weird thing is that I woke up this morning, blacked out, and then regained consciousness in the middle of the woods. And, when I got back, he was just _there_ on the couch."

      "Do you think they're connected? Maybe he's right and you _did_  bring him here!"

      "Mabel. That's impossible. I didn't want him here! This is our last summer together and the last thing I wanted to do was look after _him_." He sighed, kicking the wall out of frustration.

      "..Maybe it won't be that bad..?" she suggested, though not convincingly enough to reassure her twin that everything would be fine.

      Another sigh pushed past Dipper's lips. "Let's just figure out what we're going to tell Grunkle Stan when he gets back."

      "Tell me what-now?" Stan's scratchy, old man voice was heard from the doorway. "And who's the blond kid on my couch?"


End file.
